| 摘要 |
PROBLEM TO BE SOLVED: To provide an acoustic microphone by which a stable output can be obtained even in a hot and humid environment such as an area around steam pipes in a nuclear energy plant. SOLUTION: An alternate current theory of a mutual induction circuit is applied to the acoustic microphone. A ceramic heat-resisting material is used for a base for winding a coil 3 which is placed separately from and opposite to the surface 2b on the side other than a surface 2a of a diaphragm 2 subjected to a sound pressure. A nickel wire covered with ceramic is used for winding wire 6. A wire covered with ceramic is used for a signal wire 8 for connecting between the winding wire 6 of the coil 3 and a high-frequency oscillator 5. Further, materials and a structure resistant to high temperature and high humidity are used for fixing the diaphragm 2 and the coil 3 by welding and mechanical fastening.
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